The primary functions of this core facility are to manage the breast cancer cell line repository and to assist breast cancer investigators with cell culture based research. The facility provides shared tissue culture areas which are well equipped and stocked with all of the necessary tissue culture reagents and supplies. Breast cancer cell lines are cultured and made available to investigators as either growing or frozen cell stocks. Frozen cell stocks are replenished as required. the breast cancer cell line repository, which has a capacity of 48,000 vials of cells, is managed through a complete inventory system and a computer database. A number of tissue culture related services are offered, including mycoplasma testing, helper virus rescue assays, charcoal stripping of calf serum, and growth curve analysis of new lots of fetal calf serum and calf serum. The genetic labeling of breast cancer cells with lacZ by either transduction with a retroviral vector or transfection with a plasmid vector, the production of conditioned media from breast cancer cells and the production of large numbers of breast cancer cells for animal experiments are developing services. The shared tissue culture areas are utilized by 35 investigators, trainees and technicians from 9 different breast cancer research laboratories. These researchers generally do not have tissue culture space in their individual laboratories. The breast cancer cell line repository is used by 60 individuals from 13 different breast cancer research laboratories. Mycoplasma testing is regularly requested by all of the breast cancer laboratories. The helper virus rescue assay is a recently offered service and has been used by 3 different breast cancer laboratories. Genetic labeling of cells with lacZ has been requested by 6 breast cancer laboratories, conditioned media production has been required by 5 breast cancer laboratories, and bulk breast cancer cell production has been requested by 8 breast cancer laboratories.